Add butter to a small saucepan and melt over low heat. Add corn syrup, brown sugar, cornstarch, salt and eggs and whisk until smooth. Increase heat to medium and cook, stirring constantly, until mixture begins to boil. Remove from heat and stir in pecans and vanilla; cool 10 minutes. Refrigerate one hour, or until thickened.

Preheat oven to 350°F. Line cupcake pans with liners.

Whisk together salt, baking powder, and flour in a small bowl. Set aside.

Place melted butter in a large bowl and add brown and granulated sugars. Mix on medium speed to combine, about 1 minute.

Mix in eggs, one at a time, mixing between each addition.

Add in the buttermilk and the flour in 3 additions, mixing just until combined.

Fill cupcake liners about two-thirds full. Bake 14-17 minutes or until a toothpick comes out clean from the center. Cool completely before filling and frosting.

Beat the butter until smooth in a large bowl or stand mixer. Add brown sugar and cream until fluffy, 2-3 minutes.

Add vanilla, heavy whipping cream and salt and mix until combined.

Reduce mixer to medium-low speed and while mixer is running, slowly add powdered sugar and mix until smooth, about 1-2 minutes. Then increase the mixer to medium-high and beat until fluffy and light, about 5 minutes.

Frosting can be stored in refrigerator for up to 2 days. Let come to room temperature and if needed, re-fluff with mixer for a few minutes before using.

Scoop out the center of each cupcake and add approximately 1 tablespoon of stuffing into the cupcake cavity.

Frost cupcakes as desired (cupcakes pictured were frosted using a Wilton 1M open star tip).

Store cupcakes in an airtight container in refrigerator for up to 3 days. Cupcakes can be frozen before being frosted.